When stars the size of our sun die, they leave behind powerful stellar remnants called white dwarfs — and these white dwarfs can transform into even more extreme objects called neutron stars, composed of the densest material in the universe. However, scientists have found that conditions must be "just right" for the major makeover to occur. You can think of it like a cosmic "Goldilocks" situation.

As it turns out, the white dwarf has to be feeding on a companion star like some kind of cosmic vampire.

Neutron stars and white dwarfs are both born when stars run out of the fuel supplies needed for nuclear fusion happening in their cores, but the difference between the two lies with their masses.

Stars with masses similar to that of the sun end their lives when they run out of hydrogen in their cores. This halts the nuclear fusion process — which involves converting that hydrogen to helium — leading to the stars collapsing and shedding their outer layers to become a white dwarf with around the mass of the sun crammed into the width of Earth.

When stars with masses around eight times that of the sun collapse after running out of hydrogen in their cores, they generate enough pressure and heat in these cores to fuse the produced helium into even heavier elements. This process only ends when the star attains a core of iron. The final collapse results in a supernova explosion and creates a neutron star with a mass between one and two times that of the sun. That's the usual way neutron stars form.

However, what if there's a bridge between the white dwarf scenario and neutron star scenario? Scientists have long suspected there is indeed a pathway for a white dwarf to become a neutron star. This new work maps out that pathway, calling it accretion-induced collapse (AIC).

"In AIC, the progenitor is already a stellar remnant, and the trigger is not its own evolution but material handed to it by a companion," team leader Laurenz Thümmler of ETH Zurich told Space.com.

The researcher added that an AIC begins with a stellar remnant in the form of a white dwarf, while the traditional route to birthing a neutron star begins with a massive "living" star. Yet, in the AIC, the collapse of an overfeeding white dwarf continues in a broadly similar way to the collapse of a massive star that creates a neutron star.

As Thümmler explains, in both cases, the neutron star creation process involves the massive star's core imploding and zippy particles called "neutrinos" carrying away energy from the event. However, an important difference is in the "standard" massive star collapse scenario, the subsequent core-collapse supernova and neutron star birth happens inside a thick envelope of material that has been ejected during the massive star's death throes. In AICs, however, this thick envelope of matter is absent.

"AIC is expected to be faint and fast, and why so little matter is ejected compared with an ordinary supernova. Not all white dwarfs could undergo an AIC, and that is the essential point."

Though AICs have been theorized about for years, Thümmler and team wanted to know what characteristics a white dwarf would need in order to undergo this transformation. They set about investigating this using 3-dimesional simulations.

It's what is inside that counts

Most white dwarfs consist of carbon and oxygen. However, some stars collapse to form a white dwarf composed of oxygen, neon and magnesium. That only happens for a narrow range of stellar masses, meaning this composition represents a minority population of white dwarfs.

When carbon and oxygen white dwarfs overfeed on stellar material from a companion or donor star, they eventually reach the so-called Chandrasekhar limit, usually around 1.4 stellar masses. Above this limit, they can go supernova. They don't become neutron stars as a result of these "Type 1a" supernovas, however, but are rather completely destroyed. Oxygen, neon and magnesium white dwarfs can avoid that destruction thanks to their high densities.

"They are typically born more massive and denser than carbon-oxygen white dwarfs and therefore require less additional mass to approach the Chandrasekhar limit," Thümmler said.

However, Thümmler and colleagues discovered this isn't the only condition needed to provoke an AIC. The white dwarf can't be too greedy either.

The team found that the accretion rate, or rate at which material from the donor star falls onto the white dwarf, has to fall within a fairly narrow window to allow an AIC to occur.

"If it is too low, nova eruptions can expel much of the accumulated material again; if it is too high, winds, envelope expansion, or binary interaction can prevent the white dwarf from reaching the conditions required for collapse," Thümmler said. "The accretion has to be fast enough, and steady enough, to get it there without triggering explosive burning along the way.

"When those conditions hold, electrons are captured onto neon and magnesium nuclei. This removes the pressure supporting the star, and the collapse follows."

All this means that AICs are expected to be rare events, although the rate at which they occur remains highly uncertain.

The team also found the environment around AICs is somewhat surprising.

"We expected the most neutron-rich material, which produces the heaviest elements, to emerge along the rotation axis, since that is where the magnetically driven outflow is strongest," Thümmler said. "It does not."

Instead, the team's models revealed neutron-rich material emerging at the mid-latitudes of white dwarfs as they transform into neutron stars. This is region where the outflows of matter driven by intense magnetic fields collide with winds heated by energy-carrying neutrinos.

Thümmler explained that this is significant because it means that these events would appear different based upon the angle at which they are observed.

How to spot white dwarf transformations

Laurenz said these AICs could be identified by Vera C. Rubin Observatory and other telescopes as a bright ultraviolet and optical event lasting two to three days, potentially accompanied by X-ray emissions and longer-lasting radio emissions.

However, the neutron stars created by such events may be difficult to distinguish from stellar remnants birthed in the traditional way.

"They are expected to populate the lower end of the neutron-star mass distribution because the collapsing white dwarf has a mass close to the Chandrasekhar limit and ejects relatively little material," Thümmler said. "However, ordinary stellar-collapse channels, particularly those involving low-mass progenitors, can also produce neutron stars with masses of approximately 1.1 to 1.4 solar masses, so a low mass alone would not uniquely indicate an AIC origin."

The team isn't done investigating AICs, with Thümmler explaining there are two main approaches to take next.

"The first is to make the predicted light curves more reliable by following both the radioactive heating and energy injection in substantially greater detail," Thümmler said. "This requires distinguishing energy carried by gamma rays, which can escape relatively early from the low-mass ejecta, from that deposited more efficiently by charged particles, while also modelling how the neutron star wind heats and accelerates the heavy-element-rich material."

The team's simulations can then be used to follow the expansion of the ejecta from the AIC and calculate how the observed light curve and spectra depend on viewing angle.

"This work is currently underway," Thümmler said. "The second direction is to test the robustness of the explosion geometry, since our present models begin with a relatively simple magnetic-field configuration and more complex or tilted fields may produce different angular ejecta patterns."

The team's research is available to view as a pre-print on the paper repository site arXiv.

Using the James Webb Space Telescope (JWST), astronomers have discovered that the ring system of a tiny solar system body is even more interesting than they knew.

The object in question is Chariklo, which orbits the sun between Saturn and Uranus, at around 17 times the distance between Earth and the sun. Despite only being around 155 miles (250 kilometers) wide, Chariklo, part of the Centaur family of asteroids, possesses two thick rings.

Though Saturn is the solar system body most famous for its rings, other planets also have ring systems, albeit less prominent. That includes Uranus, Neptune, and Jupiter. However, Chariklo and the even smaller body Chiron, show that even the most diminutive bodies can develop rings. Now, thanks to the incredible sensitivity of the JWST, scientists know that the rings of Chariklo are even stranger than their initial discovery in 2013 suggested.

The team, led by researchers from the Institute of Astrophysics of Andalusia (IAA-CSIC), began observing Chariklo with the JWST in Oct. 2022. They used a technique called stellar occultation, which measures the decrease in light from a star when an object passes in front of it.

"By comparing JWST observations with those obtained during other stellar occultations over the last decade, we discovered opposite changes in the two rings: while the inner ring shows significantly higher opacity, the outer ring shows lower opacity," team leader Pablo Santos-Sanz of the IAA-CSIC said in a statement.

The changing rings of the asteroid suggest that it experiences more complex physics than previously thought. This is important because scientists had previously believed that small bodies had relatively stable rings.

"Our results force us to rethink how they form, how they evolve, and what mechanisms maintain their stability," Santos-Sanz said. "The ability to detect these changes opens a new window for understanding the evolution of these systems and, possibly, that of other ring systems in the solar system."

The cause of these changes remains a mystery.

Another milestone for the JWST and Gaia

The research doesn't just represent an important step in our understanding of asteroids and solar system rings, but it is also an important milestone for the JWST.

"Achieving this required knowing with extraordinary precision the orbit of Chariklo, the position of the star, thanks to the European Space Agency’s Gaia mission, and the trajectory of JWST itself around the L2 Lagrange point, a region of space located about 1 million miles (1.5 million kilometers) beyond Earth, away from the sun," team member Yücel Kilic of the IAA-CSIC said. "The JWST follows an orbit around this region that requires periodic corrections through station-keeping maneuvers."

During the occultation the team used in their research, Chariklo was traveling at around 5,600 miles per hour (2.5 kilometers per second) relative to the JWST.

This is incredibly fast by Earth standards, but relatively slow for objects racing through the solar system. This low speed allowed the rings of Chariklo to be resolved in unprecedented detail. Astronomers currently rely on occultation to study Chariklo and its rings, as even the JWST isn't powerful enough to directly image this small and distant asteroid.

The team's research was published on Tuesday (Sept. 9) in the journal Science Advances.

Our star and primary energy source that makes life on this planet possible may also be a cosmic cannibal. That's according to new research that suggests the sun may have swallowed a super-Earth planet billions of years ago in its early history. And our star may still be hiding the evidence.

The scientists behind this research think that the fingerprints of this violent consumption of a planet may still exist within the solar interior. Super-Earths are common occupants of other planetary systems, and these findings can explain why the solar system lacks such a world.

"Our new study suggests that a planet several times more massive than Earth may have fallen into the young sun and left a lasting chemical imprint deep inside it," Mutlu Yildiz, of Ege University, Turkey, said in a statement.

Yildiz and colleagues theorize that the sun's act of planetary infanticide may help to explain differences between observations of the sun and what is predicted by models of stellar evolution. This includes the depth of the sun's convection zone and the so-called sound-speed structure just below the convection zone.

It could also explain why the surface of the sun is depleted of the element lithium.

"By modelling the sun's evolution and comparing the results with precise observations of its interior, we find that the ingestion of a super-Earth could help explain long-standing differences between standard solar models and observations, including subtle changes in the sun's internal structure and its depleted lithium abundance," Yildiz said. "We were interested in whether these problems might have a common origin in the early chemical history of the sun."

The researcher explained that young stars like the sun during its infancy are surrounded by vast flattened clouds of gas and dust called protoplanetary discs, where substantial amounts of material can move between the disc and the star.

"Since planets are made of material that is chemically different from the gas in the disc, we wondered whether the early engulfment of a planet could have left a chemical signature inside the young sun," Yildiz said.

What happened to the sun's planetary meal?

Using advanced stellar evolution software, Yildiz and colleagues tested their idea by investigating different ways the sun could have swallowed a planet.

Their results found the best fit for the sun's current characteristics was the cannibalism of a planet between five and ten times the mass of the Earth, a type of planet called a super-Earth. This could explain the strange, unpredicted characteristics of the sun.

We thought planetary engulfment might affect the solar structure but did not expect the calculations to converge on such a specific super-Earth mass range," said Professor Yildiz. "That was one of the most interesting outcomes of the study."

The team's research is supported by previous studies that suggests one or more super-Earth planets could have formed with the orbit of Mercury, the closest planet to the sun.

These worlds would have then migrated through the protoplanetary disk surrounding the infant sun before crashing into the star.

But this new study leaves open the possibility that something else, other than this violent collision with the sun, may explain the discrepancies in measurements of the sun's interior and its lithium content. The team's model doesn't need a planet to have been totally engulfed by the sun.

Currently, this idea is based on computer modelling and unexplained solar features, but the researchers think that the predicted structural and chemical signature of a planetary engulfment could still exist within our star and could be detected.

"The earlier work proposed that a super-Earth could have formed and migrated into the young sun. Our paper asks whether the sun itself could still carry observable evidence that such an engulfment actually happened, and we believe it could," Yildiz concluded. "The next step is to see if these fingerprints can be independently detected."

The research was published on Thurs (Sept. 10) in the journal Monthly Notices of the Royal Astronomical Society.

A catalog of almost 3,000 white dwarfs that exploded as type Ia supernovas after overfeeding on companion stars indicates that dark energy, the mysterious force accelerating the expansion of the universe, is changing over time.

The discovery, in conjunction with data from the Dark Energy Survey (DES), backs results revealed from the Dark Energy Spectroscopic Instrument (DESI) published in 2024 that suggested dark energy's influence is weakening.

That means that the team's research doesn't just involve the most comprehensive catalog of type Ia supernovas; it presents the clearest picture yet of the evolution of the universe and the influence of dark energy.

"We've rebuilt 3 decades of astronomical observations into a single, consistent framework," team member Ryan Camilleri of the University of Queensland said in a statement."We combined our data with other cosmic measurements, including relic light from the Big Bang and maps of how galaxies are distributed through space.

"Instead of confirming the standard model of cosmology, which assumes dark energy is fixed and unchanging, we have more evidence that dark energy may change over time."

How do exploding white dwarfs tell us about dark energy?

White dwarfs are the smoldering stellar remnants that are left over when stars with around the mass of the sun exhaust the fuel for nuclear fusion in their cores. This ends the outward pressure that supports a star against its own gravity, meaning the star's core collapses as the outer layers are shed. The core becomes a white dwarf, and for single stars, that is the end. But around 50% of sun-sized stars have a binary companion, and this can lead to renewed activity and a change in the star's fate.

If the white dwarf and its companion are close enough together, the dead star begins stripping away the outer layers of its companion. As this material builds on the white dwarf, it pushes the stellar remnant's mass over the so-called Chandrasekhar limit, allowing it to go supernova.

These cosmic explosions are called type Ia supernovas, and their light output is so uniform that these events are referred to as standard candles. They are of vital importance because measuring how their light has been redshifted as it travels means type Ia supernovas can be used to measure cosmic distances.

"Over the years we've learned a lot more about how supernovae behave so we've been able to go back and apply that improved understanding to older data," Camilleri said. "Extensive work has been done to link observations from different telescopes with different capacities and take into account issues such as cosmic dust and galaxy mass which can affect the light coming from a supernova.

"We also incorporated more subtle effects such as gravitational lensing, which is the bending and magnification of light around large objects as it travels from a supernova to Earth."

Combined with the 2024 results from DESI, this research could change our idea of what dark energy actually is.

"Our supernova data from DES in 2024 first showed hints that dark energy may be time-varying, and this new compilation also sees a deviation from the standard model, although in a slightly different direction," Davis said. "Similarly, results from DESI found hints of variations in dark energy in its surveys of relic sound waves from the early universe.

"So, two completely independent measurements have found hints of time variation in dark energy, challenging the standard model that dark energy doesn't change."

Davis added that, as well as revealing what dark energy actually is, this research may also hold the clue to explaining how gravity and quantum physics fit together. While quantum physics (the best theory we have of how the universe operates at subatomic scales) and Einstein's theory of general relativity (our best picture of gravity) have been highly successful in their own rights, scientists have so far been unable to unite them. In other words, there is no theory of quantum gravity.

“We know these two theories are each immensely successful in their own realms, so if we can figure out how to put them together, that would be a huge step in theoretical physics," Davis continued.

This effort will receive a boost when data is added to the team's already comprehensive type Ia supernova catalog. This will include observations from the Dark Energy Bedrock All-Sky Supernova program (DEBASS), which is detecting hundreds more local supernovas than even the DES survey.

The team's results are available on the repository site arXiv.

Wrinkles on the surface of Mercury have revealed that the closest planet to the sun is shrinking faster than scientists thought.

New research suggests that Mercury is shrinking between 10% and 30% faster than had been previously estimated. The team behind this research calculated that the planet has lost nearly 12 miles (19 kilometers) of its total diameter since it formed.

The researchers think that the extremity of this shrinking has gone unnoticed previously because bombardment from space rocks over time has created craters that obscured the evidence of this process.

Scientists say determining the extent of the shrinking of Mercury is key to investigating the composition of the planet's interior.

"More shrinking means Mercury could have a larger metal core, less light elements like silicon mixed into the metal core, or a higher starting temperature," team leader Gaku Nishiyama, of the German Aerospace Center (DLR) Institute of Space Research said in a statement.

Mercury's rocky past

Like all rocky planets in the solar system, Mercury was formed 4.5 billion years ago during a violent and turbulent time in the solar system's history, as rocks and asteroids collided with each other and were bound together.

These impacts generated heat, which Mercury has been losing ever since. As the interior of Mercury cooled, it also shrank. This caused geological wrinkles in the form of scarps and ridges to develop in the rocky outer layers of Mercury.

This cooling should result in Mercury shrinking in a roughly uniform way, and that would make these shortening structures common across the planet. However, asteroid impacts throughout its history have not only created craters that obscure signs of its geological history, but have also spread debris across the surface of Mercury. This makes wrinkles tougher to spot among the accumulation of billions of years' worth of geological features.

The team combined previous maps of Mercury's geology with new observations of the entire planet's surface roughness. They found the roughest terrain of Mercury featured the fewest wrinkles.

"It made us think that there's a process obscuring shortening structures," said Nishiyama, who thinks that impact debris in the roughest regions of Mercury is covering shrinking wrinkles.

The team then used the ridges and scarps in regions less affected by the dispersal of debris to estimate the amount of contraction. This indicated that missing features in rough areas could amount to 10% to 30% extra shrinkage over the 4.5 billion-year lifetime of Mercury. That amounts to a total change in diameter of up to 14.5 miles (23 kilometers) rather than the currently estimated 2.5 to 10 miles (4 to 16 kilometers).

"30% is a little bit surprising, but the corrected amount of contraction actually makes sense to me," Nishiyama said.

There may be more surprises in store. Nishiyama believes that the updated figures could still be an underestimate. This estimate is based on data collected by NASA's MESSENGER probe, which ended in 2015. MESSENGER could only distinguish features larger than around 3 miles (5 kilometers) across.

In November 2026, the BepiColombo mission will start conducting scans of Mercury's surface in much higher resolution than this, and that could reveal even more shrinkage features.

The team's research was published on Thursday (Sept. 10) in the journal Geophysical Research Letters.

Though their origins may be shrouded in mystery, fast radio bursts (FRBs) could be used to probe some of the universe's biggest puzzles. This includes probing the nature of dark matter, the invisible sort of matter that somehow dominates the universe, and dark energy, the mysterious force causing the expansion of our universe to accelerate. They could even shed light on the mysteries of neutrinos, or "ghost particles." Let's dive into how.

FRBs are brief but intense blasts of radio waves currently thought to erupt from rapidly rotating dead stars with the universe's strongest magnetic fields, called magnetars. As FRBs travel billions of light-years to reach Earth, they pass through dense clouds of gas and dust in galaxies. This "cosmic fog" changes the original FRB signal. What this means is these blasts of radio waves carry the fingerprints of how matter in the universe is distributed.

Mapping the distribution and "clumpiness" of ordinary matter in galaxies can then help trace the distribution of dark matter, the effect of dark energy and the mass of neutrinos.

"We've established that FRBs are a leading probe of the distribution of matter in the universe," team leader Kritti Sharma, a graduate student working with Vikram Ravi, a professor of astronomy at the California Institute of Technology (Caltech) and also part of the team, said in a statement. "These FRB data can be used to enhance cosmology experiments that are trying to answer questions about dark matter, dark energy, and the mass of neutrinos."

For this research, Ravi and Sharma analyzed a sample of about 100 FRBs. This represents the first time scientists have used FRBs to directly measure the impact of so-called "feedback" from galaxies on the clumpiness of matter in the large-scale regions between galaxies.

Cosmic ghosts and the dark universe

Ordinary matter, composed of atoms made up of electrons, protons and neutrons, accounts for just around 5% of the universe's energy/matter budget despite comprising stars, planets, moons, our bodies, next door's cat and everything we see around us on a day-to-day basis.

Of this budget, the other 95% is composed of dark energy (68%) and dark matter (27%). It's little wonder that scientists are very keen to better understand these two aspects of the cosmos, sometimes collectively referred to as the "dark universe."

Things get even more murky when considering how, of that 5%, the second most abundant particles in the universe, aside from particles of light or photons, are neutrinos. These get their nickname of "ghost particles" because they interact with other matter particles so infrequently that approximately 100 trillion neutrinos pass through your body every second without leaving any trace. This is possible because neutrinos are virtually massless, and scientists are keen to accurately measure the mass of these cosmic ghosts.

These three mysterious elements of the cosmos have played a vital role in the evolution of large-scale cosmic structures like galaxies and galaxy clusters. That means, in turn, that measuring the clustering of matter can reveal details about the aspects of the universe that influenced that clustering.

However, to do that, scientists also have to understand how other factors smooth out cosmic clumpiness. That includes the energy pumped out from the hearts of galaxies by feeding supermassive black holes, a type of cosmic feedback that smooths out clumpy cosmic matter lying outside galaxies.

"The feedback process thins the gas around the galaxies, redistributing matter across vast distances. It smooths out clumps of matter in a way that looks astonishingly similar to what massive neutrinos do, or what dark energy or dark matter theories predict," Ravi said. "Unless scientists can independently measure this contribution from feedback, they can't tell these effects apart."

That's where FRBs come in.

The researchers found that, while galactic feedback does indeed smooth surrounding material, making it less clumpy, the effect is weaker than has previously been measured.

"Our analysis of FRBs reveals how gas ejected by astrophysical feedback suppresses cosmic structure," team member Elisabeth Krause of the University of Arizona said in the statement. "This is amazing considering we only had about 100 FRBs in our sample. It's only the beginning."

The investigation of the universe with FRBs could get a major boost in 2029 when Caltech's Deep Synoptic Array (DSA) begins operating in Nevada. This powerful radio telescope is expected to find tens of thousands of FRBs, a major boon for cosmology.

The team's research was published on Tuesday (Sept. 8) in the journal Nature Astronomy.

A "forbidden" merger between two massive black holes may not have been quite as impossible as previously thought. That's according to new research that suggests the black holes involved were smaller than expected.

On Nov. 23, 2023, the gravitational wave detector LIGO (Laser Interferometer Gravitational-Wave Observatory) detected tiny ripples in spacetime caused by the merger of two black holes. What was incredible about this signal, designated GW231123, was that it seemed to be the result of a black hole with 140 times the mass of the sun colliding with another that holds 100 solar masses.

This raised eyebrows among researchers because usual models of stellar evolution struggle to account for such massive black holes, especially ones that seemed to be spinning as fast as these two. While scientists have been attempting to explain how such an odd black hole binary could form. The team behind this new research suggests it doesn't need to be explained at all. They think that the masses of these black holes were an illusion.

The key to this illusion is a phenomenon called gravitational lensing, first predicted by Albert Einstein's 1915 theory of gravity, general relativity, which also first predicted the existence of gravitational waves. This theory says objects with mass cause the curvature of space and time, united as a four-dimensional entity called "spacetime." The more mass an object possesses, the greater the curvature, and because gravity arises from this curvature, the greater the gravitational influence.

Gravitational lensing occurs when light from a background object passes a massive foreground object. The foreground object can warp the fabric of spacetime in such a way that the light's path is curved. This means light from the same background source can reach Earth at different times, depending on how much that light was diverted.

This difference in travel time can magnify a background source, and it has been used to great effect to observe distant and ancient galaxies ordinarily too faint to be seen.

This research team thinks the effect also applies to gravitational waves, suggesting the signal GW231123 is an example of gravitationally lensed ripples in spacetime that made the black holes appear larger than they actually are.

"Like light, gravitational waves can also be deflected, magnified and split into multiple signals by massive objects," team member Miguel Zumalacárregui, group leader in the Astrophysical and Cosmological Relativity Department at the Albert Einstein Institute (AEI), said in a statement. "For gravitational waves, diffraction and interference effects give us an additional way to identify and study lensed signals."

To investigate this possibility, the team developed a mathematical model of gravitational lensing and created software powerful and fast enough to analyze it.

"If we assume that GW231123 was deflected and distorted by a compact object of about 190 to 850 solar masses — or by an extended structure such as a globular cluster — we can understand the observed high masses," said team member Srashti Goyal, who was based at the AEI when conducting the research. "Moreover, the lensing interpretation does not require unusually high spins."

When the team modeled the event with that consideration factored in, they found the merger involved a system with a mass of 140 solar masses, rather than the 240-solar-mass system initially theorized.

The team doesn't quite know what massive object is responsible for lensing the gravitational wave signal GW231123. But no matter what it is, if the team is correct, the lens could be something quite special.

"The nature of the lens remains a major mystery in our analysis, as individual compact lenses with 100 to 1,000 solar masses should be exceedingly rare," Zumalacárregui said. "Future work will need to establish whether such lenses can form, or whether an ensemble of lighter objects, including stars, can explain this event."

The team can't yet conclusively say if GW231123 is the first gravitationally lensed gravitational wave signal. Finding future signals of the sort will require upgrades to the sensitivity of detectors like LIGO.

Though even before that happens, the research does point to the utility of gravitational wave astronomy to study some of the universe's most violent events.

The team's research was published on August 25 in the Astrophysical Journal Letters.

Using the ALMA (Atacama Large Millimeter/submillimeter Array) radio telescope, astronomers have watched as two stars come together to form a massive stellar binary. The observations revealed that these stars didn't form from the same collapsing cloud of gas and dust, as most binary stars are assumed to form, but instead came together later in their infancy.

Here on Earth, we are slightly prejudiced by our single sun to view stars as somewhat solitary bodies. However, around half of sun-sized stars in the Milky Way have a companion star. This percentage of stellar partnership rises to around 90% of massive stars. Eventually, these massive stars go supernova and shape their cosmic surroundings. Thus, understanding these binary systems is vital to our understanding of stars and of galaxies in general.

The team behind this research initially observed the still-growing massive stars, or protostars, in the binary system IRAS 07299−1651, located around 5,300 light-years away in 2019. At first, the researchers didn't see anything that suggested these stars didn't form from the same disk-shaped cloud of gas and dust that later fragmented. However, one thing really stood out: the disks of material surrounding and feeding these protostars are oddly misaligned.

Over the course of eight years, the team mapped subtle shifts in the position of the stars using ALMA in addition to the Very Large Array (VLA), as well as infrared images from the James Webb Space Telescope (JWST) and the Very Large Telescope (VLT).

"For the first time, we were able to watch two massive stars move around one another while they were still being born," team leader Yichen Zhang of Shanghai Jiao Tong University, China, said in a statement.

The team was able to reconstruct the full 3-dimensional structure of IRAS 07299−1651 for the first time, obtaining details about how the stars orbit each other, the way their disks are aligned, and the angle at which they blast jets into space.

"Each telescope revealed a different piece of the puzzle," team member Rubén Fedriani, of the Instituto de Astrofísica de Andalucía (IAA) in Granada, Spain, said. "The combination of radio and infrared observations provides the most exquisite detail on the formation of this massive protobinary system."

Unexpected chaos

The team's observations took them by surprise. They were expecting these stars to orbit each other in neat, near-circular orbits. Instead, the orbits were found to be highly flattened or "eccentric," almost parabolic.

If the stars had formed from the same disk of material, then even after it fragmented, the individual disks surrounding the stars would be aligned. However, that wasn't the case; the disks are tilted at a sharp angle to each other and to the orbits of the stars.

"It felt like solving a three-dimensional puzzle," team member Yao Wang of Shanghai Jiao Tong University said. "Each new observation added another piece, and eventually the orbit, disks, and jets all came together into a single, coherent picture."

The chaotic structure of IRAS 07299−1651, as observed by the team, is difficult to explain if the two stars emerged from the same disk of material.

Instead, the researchers theorize that the two stars were born in individual clouds of gas and dust, before a chance encounter brought the two infant stars and their respective natal cocoons together.

Tracing back the orbits of the stars, the researchers found that this encounter likely occurred around 60 years ago. Considering stars live for billions of years, that is an instant on a cosmic timescale. The disk-shaped pockets of material around the stars have thus far survived the encounter, retaining their well-defined structures.

"This study demonstrates that the early lives of stars can be quite chaotic, with a chance encounter leading to this gravitational dance and stellar coupling," team member Jonathan C. Tan of the University of Technology and the University of Virginia said.

What the team can't yet establish is whether these stars are destined to stick together or if they will eventually move apart. Indeed, this fate may not have been sealed yet; interactions with the surrounding gas could determine what shape this system takes in the future.

The team hopes that further observations of IRAS 07299−1651 will help to better understand what the future holds for these stars.

In the meantime, the long-term monitoring approach adopted by the researchers could provide scientists with a powerful new way of investigating other young massive binary systems. This could reveal how common encounters like this are and if more binary systems are composed of stars brought together by chance encounters.

The team's research was published on Tuesday (Sept. 8) in the journal Nature Astronomy.

A photon, or particle of light, from the biggest cosmic explosion since the Big Bang, nicknamed "the BOAT" (for the brightest of all time), should not have reached Earth. That is, unless it defied rules defined by Einstein. Now scientists may know how it did this, with new research suggesting how the high-energy photon may have survived a journey of more than two billion light-years without being absorbed.

The BOAT, a gamma-ray burst officially designated GRB 221009A, was first detected on Oct. 9, 2022. Among the ocean of photons from the event that rained down on our planet was the highest-energy photon ever detected originating from a gamma-ray burst. It was detected by Carpet, an ultra-high-energy cosmic-ray detector located at the Baksan Observatory in the Russian Caucasus.

The problem is, according to all current rules of physics, a particle with such high energy shouldn't reach Earth from an explosion occurring such a vast distance away. That's because space isn't empty; it is filled with a "fossil" radiation field of photons left over from just after the Big Bang called the cosmic microwave background (CMB). It should be virtually impossible for a high-energy photon to travel 2 billion light-years without interacting with a CMB photon and being transformed. And still it came.

"We started from a very simple question: how did this photon survive a journey that, according to known physics, should have destroyed it?" team leader Giorgio Galanti from the Italian National Institute for Astrophysics (INAF) said in a statement. "The new data from the Carpet experiment showed us that the explanations proposed so far were no longer sufficient.

"We therefore looked for a theoretical scenario capable of consistently describing what we observe, without resorting to arbitrary corrections to the equations."

A hypothetical transformation

To investigate the mystery of how this high-energy photon reached our planet, Galanti and colleagues turned to incredibly light hypothetical particles called axion-like particles (ALPs).

ALPS could serve as a solution to this puzzle via a mechanism that would allow photons to transform into ALPs as they travel and then convert back into photons as they reach the Milky Way. The problem is that this still can't account for such a high-energy photon.

This team combined the idea of ALPs with a proposed violation of one of the fundamentals of Einstein's 1905 theory of special relativity called "Lorentz invariance."

In short, Lorentz invariance says that observers moving at different speeds should experience the same physical laws. The team tested the idea that Lorentz invariance could be violated at high energies, thus changing how photons propagate through space.

In the scenario devised by the team the photon would have avoided being wiped out by interactions with the CMB as it would avoid interactionc with these fossil photons.

The new research therefore implies that at high enough energies, photons can take a "fast lane" through a transparent universe, dodging the physics that would normally force their destructive transformation.

Interestingly, there is some evidence relating to the BOAT that seemingly backs this theory. According to the picture developed by the team, this high-energy photon should have arrived at Earth around one hour after lower-energy particles of light originating from the BOAT. Indeed, that is exactly what happened.

"The most interesting aspect of our work is that, for the first time, it brings together two ideas that until now had been developed separately," team member Marco Roncadelli of the National Institute for Nuclear Physics (INFN) said. "If future observations confirmed this scenario, the universe would become a natural laboratory for studying quantum gravity at energies enormously higher than those achievable by any accelerator built on Earth."

The team's research is available on the repository site arXiv and has been accepted for publication in the journal Physical Review Letters.

Scientists may finally know why Venus, Earth's twin, lacks a moon, finding that the hottest planet in the solar system may have consumed its own natural satellite.

Venus is often referred to as Earth's twin due to its size, mass, rocky composition, and distance from the sun, but there are some glaring differences between the two planets. Aside from Venus' blisteringly hot temperature, which could melt lead, incredible surface pressure, violent high-speed winds, and clouds of sulfuric acid, one of the key differences between Earth and Venus can be seen from afar. While our planet has a constant companion in the form of the moon, Venus lacks a moon of its own. In fact, the only solar system planets lacking moons are Venus, the second planet from the sun, and Mercury, the closest planet to the sun.

One question that scientists have puzzled over for years is whether Venus always lacked a moon, or if the hottest planet in the solar system once had a natural satellite and somehow lost it. Now, a team of researchers may have arrived at an answer, determining the fate that would have befallen a hypothetical moon orbiting Venus.

"I have always had a fascination with moon formation and evolution in the solar system, and particularly with Venus since my research is centered around its evolution and potential for past habitability," team leader Stephen R. Kane of the University of California, Riverside told Space.com. "Venus is Earth's twin, and both are nearly identical in size, mass, and composition. However, Earth has a large moon, and Venus has no moon at all, not even a small captured satellite.

"Venus undoubtedly experienced large impacts, just as Earth has, and so has had as much, if not more, opportunity to form a moon similar to what we see in our own skies."

Kane and colleagues constructed a simulation to test their ideas of what could have become of the Venusian moon.

"The work involved going back to fundamental physics and creating the simulation from the ground up, which I validated by ensuring I could reproduce the evolution of the Earth-moon system," Kane said. "The moment I realized that our model provided a complete explanation for Venus not having a moon was an exciting one!"

Did Venus consume its own moon?

The team modelled a gravitational tug-of-war between Venus, a hypothetical moon, and the sun, following this forward over billions of years.

"This is the same physics that governs our own moon, which is slowly drifting away from Earth. We ran the calculations across a wide range of possibilities for how fast Venus was spinning and how massive its moon might have been, using two independent mathematical descriptions of how tides work," Kane explained.

The researcher said that this was done so the conclusions reached wouldn't hinge on one set of assumptions. They found in most cases a Venusian moon would not drift safely outward the way ours does. Instead, the modelling showed that a moon orbiting Venus would eventually reverse its course and spiral inward, causing it to be torn apart by the planet's gravity.

Kane and colleagues found that possessing an intimidating size wouldn't guarantee a Venusian moon's survival, either.

"An interesting aspect is that a heavier moon is destroyed faster, since a massive moon would drain Venus's spin so efficiently that it hastens its destruction," Kane added.

But are there any circumstances under which a Venusian moon could have survived?

"Survival came down to two main things: Venus had to be spinning fast when the moon formed, with a day shorter than about 12 hours, and the moon couldn't be too massive, up to roughly the mass of our own moon," team leader Stephen R. Kane of the University of California, Riverside told Space.com. "In that narrow window, the moon migrates outward and stabilizes, much as Earth's did. Outside that range, the moon is unfortunately doomed to be consumed by Venus.

"So a surviving moon would have had to be modest in size, orbiting a rapidly spinning early Venus, which are conditions that don't match what we think early Venus was actually like."

We may never conclusively know if Venus has indeed destroyed its own moon, as Kane thinks that collecting direct evidence from astronomical observations will be very difficult.

"Finding direct observational evidence is pretty tough. A moon lost billions of years ago would leave little to no direct trace we can point a telescope at today, so we can't observe the event itself," Kane said. "However, there are indirect avenues. For example, if a moon was destroyed and its debris rained down on Venus, it could have left a chemical fingerprint in the planet's surface or atmosphere, and upcoming missions to Venus, including NASA's DAVINCI (Deep Atmosphere Venus Investigation of Noble gases, Chemistry, and Imaging) probe, will measure atmospheric composition in detail."

If missions such as DAVINCI could help us develop a better understanding of the Venusian interior, then this would also improve the models such as the one used in this research. That is because the outcomes of such models depend on properties of Venus's interior, which aren't currently well understood.

"There's a broader test beyond our solar system because our results predict that slowly rotating, Venus-like planets around other stars should generically lack large moons, so as astronomers begin searching for moons around exoplanets, that's a prediction that can eventually be checked against real data," Kane said.

Kane and colleagues don't intend to rest on their laurels while further data from Venus or even Venus-like exoplanets are delivered. They have plenty to work on in the meantime.

"There are numerous implications of our work that I would like to explore further. These include the compositional and atmospheric effects of a Venusian moon consumption event that may be testable now," Kane concluded. I would also like to explore similar effects for Mercury and Mars, and conduct further studies on exoplanet cases where such moon collision scenarios may have occurred."

The team's research is available as a pre-peer-reviewed paper on the repository site arXiv.

Scientists have spotted the first hints that Albert Einstein's formulation of gravity operates in the quantum realm.

The hints have to do with observations of a falling quantum object, and though this may not seem like a huge deal (literally, we are talking about atoms here), it could be an important step on the road to a theory of ... everything.

To start, we have to go back to the early years of the 20th century. Consider Einstein's iconic theory of gravity, general relativity, and the elusive realm of quantum mechanics. While the former describes the universe on scales of planets, stars and black holes, even demonstrating how galaxies and galaxy clusters formed, the latter describes the counterintuitive physics found on scales smaller than atoms. But there is a problem: these two important theories don't play well together.

There is no quantum theory of gravity. However, scientists think we're getting closer to one.

A team of researchers has performed an experiment to find the point where quantum mechanics and general relativity meet. Namely, how the quantum properties of atoms change as those atoms fall under the influence of gravity.

"This is a unique paper, in the sense that it combines a hard experiment with a far-reaching theoretical interpretation, about one of the most fundamental questions in physics: How can gravity, described by Einstein's theory of relativity, and quantum theory, be unified into one understanding of the universe?" team leader Ron Folman of the Ben-Gurion University of the Negev said in a statement. "These two pillars of modern physics have so far eluded all attempts at a unified theoretical framework, but this complex experiment gives more hints as to how such a unification may be achieved."

Elevators and equivalence

At the cornerstone of the team's experiment is an important element of general relativity called the equivalence principle.

The equivalence principle states that, for an observer in free fall, gravity should disappear. If that sounds confusing, consider this popular analogy: You are inside a closed elevator with no view of your surroundings. You feel heavy. You might drop a ball, and it would fall to the floor of the elevator. Why would these things happen? Well, there are two options.

You might be sitting stationary on the ground floor, or the elevator could be moving upwards at an acceleration equal to the gravitational field strength of Earth, 9.8 meters per second squared. You can't tell the difference between gravity and acceleration. That's the equivalence principle.

Now, let's shake that up. Suddenly, you can't feel weight anymore. You drop the ball, and it floats. Gravity has disappeared, or the upward acceleration has ended. Inside the elevator, two things may have happened, and you can't distinguish between these two either. The elevator cable may have snapped, and you may now be in free fall, or the upward acceleration may have carried you to space and then ceased.

The big question now is: How do you test this on a quantum scale, especially for particles that behave as waves as they travel?

Wave hello to quantum gravity?

To measure the equivalence principle at a quantum scale, the researchers turned to a piece of equipment called the Quantum Galileo Interferometer. This allowed them to split the quantum wave associated with a traveling atom into two paths. One was held in place while the other was allowed to fall freely.

The team then reunited the wave to observe the changes gravity had introduced to the falling wave.

For the experimental subjects, the team chose a cloud of rubidium atoms, which they cooled to just above absolute zero. These were placed close to the surface of a specially designed atom chip. Using microwave pulses, the scientists placed the atoms in what is known as a quantum superposition.

A superposition is one of those really weird things unique to quantum physics, effectively allowing a quantum system to simultaneously exist in two or more contradictory states. In this case, the superposition allowed each atom to travel along two different paths at the same time.

Magnetic fields generated by the atomic chip applied an upward push along one path, counteracting the downward pull of gravity and holding it stationary. The other path was subjected to magnetic pulses pushing the atoms upwards. The pulses were then shut off, allowing the atoms to fall freely under gravity like a ball thrown into the air.

When the waves were reunited, the team used an effect called interference, which occurs when the peaks and troughs of two misaligned waves meet, to measure changes in the free-falling wave.

This represented the first time that the effects of gravity and free fall on the phase of a quantum wave had been measured.

However, while this is an effective demonstration of Einstein's equivalence principle in the quantum realm, it isn't a demonstration of quantum gravity. Yet it remains a step along a frustratingly long road physicists have been traveling down for over a century with no end in sight.

"We have no consistent theory telling us why quantum physics should fail," team member Vlatko Vedral said in the statement. "This experiment pushes quantum mechanics into one of its most intriguing frontiers, gravity, and shows that, once again, its predictions hold."

The team's research was published on Wednesday (Sept. 2) in the journal Science Advances.

Astronomers have used the MeerKAT radio telescope to detect hydrogen gas billions of light-years away from us — from a period when the cosmos was billions of years younger than its current age of 13.8 billion years.

The research may provide astronomers with a new way of mapping the large-scale structure of the universe. The technique would rely on charting out where hydrogen, the universe's lightest and most abundant element, is located across the cosmos. It's known as hydrogen intensity mapping.

Neutral hydrogen emits a faint radio signal that astronomers call the 21-centimeter line. As the cosmos expands under the influence of dark energy, the wavelength of this radio signal is stretched, or "redshifted." The extremity of the redshift allows astronomers to determine how long a particular signal has been travelling to us and thus what period of the universe the hydrogen that emitted it existed in.

Using the 21-centimeter line, hydrogen intensity mapping allows astronomers to trace radio emissions from hitherto unseen galaxies and build a 3D picture of the largest structures in the universe. Up until this point, however, this technique has relied on combining radio wave detection with observations from galactic surveys operating with visible light, or electromagnetic radiation our eyes have evolved to see.

This new research defies that trend, building a hydrogen intensity map using radio waves detected by the MeerKAT radio telescope, made up of 64 antennas in the Meerkat National Park in the Northern Cape of South Africa.

"This is a very exciting milestone," team leader Sourabh Paul said in a statement. "Hydrogen intensity mapping has long been seen as a promising way to map the universe efficiently, but the signal is extremely faint and difficult to isolate from foreground emission, human-made radio-frequency interference, and instrumental effects.

"Detecting it directly with MeerKAT shows that this technique is becoming a practical tool for cosmology."

Mapping with MeerKAT

The team behind this research analyzed around 96 hours of MeerKAT observations, finding signals from hydrogen dating back 4 billion to 5 billion years. This hydrogen spans distances of many million light-years, similar to the distance between the Milky Way and our neighbor galaxy, Andromeda.

The achievement represents a step forward in the usefulness of hydrogen mapping.

"Neutral hydrogen is one of the key ingredients for understanding how galaxies form and evolve," team member Zhaoting Chen of the University of Edinburgh said in the statement. "With intensity mapping, we do not need to detect every individual galaxy. Instead, we can measure the collective signal from hydrogen across large cosmic volumes, giving us a new way to study both galaxy evolution and the underlying matter distribution of the universe."

Future cosmological surveys could greatly benefit from the advancement of hydrogen mapping. This will be a major factor when the Square Kilometre Array Observatory (SKAO), currently under construction in the Murchison region of Western Australia and the Karoo region of South Africa.

"MeerKAT continues to open new windows for cosmology," team member Laura Wolz of the University of Manchester in the U.K. said in the statement. "The fact that this signal can be extracted from observations that were not originally designed for hydrogen intensity mapping is very encouraging. It shows the enormous scientific value of MeerKAT data and points the way to future observations with SKAO."

The team will now focus on collecting further observations with MeerKAT that cover larger areas of the sky over longer periods of time. This should provide astronomers with even more detailed hydrogen maps that could, in time, help understand how the largest structures in the cosmos took shape over the course of billions of years.

"This was a challenging data analysis process, requiring a detailed understanding of the many sources of contamination that can affect such a faint measurement," team member Mario G. Santos of the University of the Western Cape, Australia, said in the statement. "It is particularly remarkable that the data used in this study were taken in 2018, when MeerKAT had only just started science operations.

"There is now a rich trove of MeerKAT data waiting to be explored with this method."

The team's research was published in the July edition of The Astrophysical Journal Letters.

Scientists are closer than ever before to understanding how stars forge the elements that comprise our planet, bodies and pretty much everything else around us — and they're gaining a clearer picture of where star explosions fit into the story.

New research reported in two different papers looks at how stars forge elements as they explode and how these supernova explosions spread those elements — and other elements stars have forged during their lifetimes — throughout the cosmos.

Astronomers have been studying the bright supernova deaths of massive stars for centuries, but they still don't quite understand how these explosions proceed.

The first paper looked at one way to investigate supernovas. It uses a radioactive element produced by these explosions called titanium-44, which lingers long after supernovas fade. Researchers have now collected experimental evidence that determines how much titanium-44 is created in a supernova, finding that these cosmic explosions produce 35% more of this element than expected.

With this knowledge in hand, scientists can now develop robust computer models of supernovas and compare these models with astronomical observations. This could bring them much closer to understanding how these explosions progress.

"It's exciting to see just how far the field has come," Christopher Cousins, a postdoctoral researcher in the University of Surrey's Nuclear Physics Group, said in a statement. "A measurement like this would have been considered out of reach only a couple of decades ago, but it now gives us new insight into one of the biggest unanswered questions in astrophysics."

The second paper honed in on a particular brand of stellar explosion called a Type I supernova. These occur when a dense stellar remnant called a neutron star drags material from a companion stellar body. The intense gravitational influence of the neutron star — a stellar corpse that has one to two times the mass of the sun crammed into a body about 12 miles (20 kilometers) wide — means that, when this stolen stellar matter hits their surfaces, a thermonuclear explosion is triggered.

These blasts forge heavy elements and release incredible amounts of energy, some in the form of X-ray bursts.

The authors of this paper, hailing from the Facility for Rare Isotope Beams (FRIB) in Michigan, studied the nuclear reaction that triggers X-ray bursts in greater detail than has been possible before.

This revealed the long-debated role of the so-called nickel-copper cycle, the temporary trapping of nuclear material during supernovas. Scientists previously didn't know if material was trapped in the nickel-copper cycle during X-ray bursts.

This research reveals that this does happen, but only in small proportions. It gives scientists a clearer picture of how Type I supernovas proceed.

"Despite decades of research, we still don't fully understand the nuclear reactions that power some of the universe's most spectacular stellar explosions," said Gavin Lotay of the University of Surrey.

"These two studies give us a much clearer picture of how these explosions happen, allowing us to compare our models more closely with astronomical observations and bringing us closer to understanding how the chemical elements are created and spread throughout the universe," he added.

The two papers were published in the July edition of the journal Physical Review Letters.

New research suggests that dust from meteorites contains a "fossil record" dating back to the formation of the sun. The research reveals that magnetism played a far greater role in the birth of the solar system than had previously been suspected.

Around 4.6 billion years ago, the solar system was a cloud of gas and dust, known as a solar nebula. Over the next few million years, this cloud began to flatten, forming a donut-shaped ring or torus with a budding star gathering mass at its core. Eventually, planets would form within this so-called protoplanetary disk.

Scientists have always theorized that gravity was the main sculptor during this early era. But the new study suggests that gravity had major assistance from magnetism. The signature of this additional cosmic artist was found within grains of dust sealed in DOM 08006, a meteorite recovered from Antarctica in 2008.

The grains found by the team are calcium-aluminum-rich inclusions (CAIs), which are thought to have formed during the first 200,000 years of the solar system. That potentially makes them the oldest samples of solar system material ever seen.

"We know they are the oldest things we have of the early solar system," team leader Cauê Borlina of Purdue University said in a statement. "But CAIs are very complex and are not all the same, even within a 1-millimeter piece of the meteorite. So we have to carefully identify what types they are."

These CAIs indicated that there was a magnetic field in the proto-solar system even during its solar nebula phase. This magnetic field would have been stronger than Earth's magnetosphere and, as such, would have influenced the flattening of the solar nebula.

"This transition, from a spherical cloud to a protoplanetary disk, is one of the most significant events in all of solar system history," team member Benjamin Weiss, of the Massachusetts Institute of Technology (MIT), said in the same statement. "It has long been theorized that gravity caused this, but our measurements show magnetism likely played a role."

A new spin on early solar system magnetism

In the newly forming solar system, a magnetic field would have been generated when charged particles were sent spinning through the collapsing cloud of gas and dust that birthed the sun. This plasma would then have sustained that field.

As such, that magnetism must have affected the material in the solar nebula that would become the solar system. For that reason, the team reasoned that the strength of this field should be "locked in" to materials from the time as remanent magnetization. This matter could make its way to Earth in meteorites.

In fact, the same scientists who conducted this research previously found evidence of a magnetic field that existed 2 million years into the formation of the solar system, baked into meteorites. That's an impressive and important find, because this magnetic field would have helped planets like Earth form — but the sun was already around by that point. Thus, the team was after an earlier magnetic field, one that predated our star.

"Nowadays, people don’t debate whether magnetism is present when planets are forming. But the debate is around the very early solar system, before planets are forming, when there’s just a disk," Borlina said. "That's where the debate still resides, and that’s where we’re operating now."

DOM 08006 is one of the most unspoiled or "primitive" meteorites ever discovered, retaining and preserving materials, including CAIs, as they were when the sun was forming.

"Other meteorites went through many different processes over this 4.5 billion-year history," said Weiss. "They were formed in the solar nebula, then added to bodies with water, then got destroyed, moved to the asteroid belt, and then landed here. But somehow, DOM has experienced less alteration than any other meteorite."

If a magnetic field existed during the earliest stage of the solar system, it should be observable in the matter that makes up DOM 08006.

The team was able to isolate and identify a handful of CAIs that contained inherently magnetic minerals such as iron, which they tested to measure any magnetism they had retained.

Studying these grains, the researchers found evidence of a magnetic field 12 times stronger than that of Earth. They think this magnetic field may have played a crucial role in the evolution of the solar system.

"We think these kinds of magnetic fields were helping to move gas from the protoplanetary disk inward toward this central star, the sun,” Borlina said. "Gravity is also playing a role. But we are now showing that, if you want to fully understand how the sun and planets formed, you should include magnetic fields in the ingredients that make them."

The new study was published Aug. 7 in the journal Proceedings of the National Academy of Sciences.